Add imessage channel plugin

iMessage bridge for Claude Code. Reads ~/Library/Messages/chat.db
directly for history and new-message polling; sends via AppleScript
to Messages.app. macOS only.

Built-in access control: inbound messages are gated by an allowlist
(default: self-chat only), outbound sends are scoped to the same
allowlist. The /imessage:access skill manages allowlists and policy.

Requires Full Disk Access and Automation TCC grants — both prompted
by macOS on first use.

Ships full source — server.ts runs locally via bun, started by the
.mcp.json command.

external_plugins/imessage/package.json

@@ -0,0 +1,16 @@
+{
+  "name": "claude-channel-imessage",
+  "version": "0.0.1",
+  "license": "Apache-2.0",
+  "type": "module",
+  "bin": "./server.ts",
+  "scripts": {
+    "start": "bun install --no-summary && bun server.ts"
+  },
+  "dependencies": {
+    "@modelcontextprotocol/sdk": "^1.0.0"
+  },
+  "devDependencies": {
+    "@types/bun": "^1.3.10"
+  }
+}